Mercury switch relay



April 12, 1938. c. H. LARSON -ET A1.

MERCURY SWI TCH RELAY Filed 001. 25, 1955 WVIMIWWM Patented Apr. 12, 1938 PATENT OFFICE MERCURY SWITCH RELAX Carl H. Larson, Elkhart, Ind., and Daniel J. McCarthy, Elgin, Ill., assignors to The Adlake Company, a corporation of Illinois Application October 25, 1935, Serial N0. 46,6a6

18 Claims.

This invention relates to mercury switch relays of the type in which a. floating armature sealed within a switch envelope is moved in response to a relay coil to displace more or less mercury, and thus change the condition of the electrical circuit through the electrodes.

Some of the more important objects of the invention are as follows: To provide a high speed relay of the type which is capable of opening and closing a circuit several .times per second; to provide a switch mounting in which the position of the switch with respect to the relay coil may be accurately determined and fixed at the factory; to shield all projecting portions of the switch envelope, so as to protect the switch from accidental blows and obscure the arc which occurs when the relay is used with high inductive loads; to simplify the iron circuit associated with the relay coil; and to reduce the cost of the relay unit- A A: l

Further `and other objects and advantages will become'ap'parent 'as the disclosure proceeds and the descriptionfisread lin conjunction with the accompanying drawing,fin"which Fig. 1 is a front elevational view of a relay constructed in accordance with this invention;

Fig. 2 is a vertical, sectional view taken on the line 2--2 of Flg..1; Y

Fig. 3 is a plan view of the relay (the scale be- 30 ing somewhat reduced); w f

Fig. 4 shows a modied form of the invention; Fig. 5 is a wiring diagram showing the application ofthe switch to an autocall system; and

y Fig. Gis a fragmentary view of anotherform 35 for-the central electrode.

The disclosurefofa: preferred form of the invention isi-madeyfor'thepurpose of complying with`sectionfiri888 of the revised statutes, but it will be understood that the claims are to be con- 4o strued as broadly as the prior art will permit.

and I3 are adapted to be connected to the signals which are to be operated; clips Il and I5 are adapted to connect the relay coil with the con- Y 50 trol circuit; and clips I6 and I1 are adapted to be'connected to a suitablesource of power for operating the signals.

The relay I0 comprises a coil Ill having a core opening I! adapted to receive a mercury v 55 switch 20 of. the mercury displacement type.

The switch comprises a glass envelope 2l, preferablylof borosilicate glass, through the base of which electrodes 22 and 23 are sealed, the latter being encased Within a glass sleeve 24 for a portion of its length and above that by a sleeve 25 5 ofrefractory material, which terminates in a cup 26 into which the bared end of the electrode 23 projects.

A displacer generally designated 21, comprising a sleeve 28 of refractory material over which a l0 sleeve 29 of magnetic material is telescoped, constitutes the-armature of the switch. When the relay coil I8 is energized, the displacer 21 is lowered by the action of the magnetic flux, vr'th the result that a suflicient amount of mercury 15 is displaced to establish contact between the mercury that is normally within the cup 26 and that which is within the envelope proper. Upon deenergizing the coil I8, the displacer rises to its position of floating` equilibrium and the mercury 20 level again falls to the position shown in Fig. 2.

When the relay is being used for operating certain types of signals, such as call signals of the bell clapper type, it is necessary for the switch to be adjusted, so that it is capable of opening and 25 quency. Means are therefore provided for fixing the uppermost limit of the switch within the coil as determined by tests at the factory, and then providing a retainer for holding the switch in such position. 35

'I'he proper position of the switch within the coil is determined empirically at the' factory, and, when once this has been determined, a bakelite sleeve is slipped over the lower portion of the switch envelope and secured in place 40 by a sealing compound 36 inserted injthe projecting end of the sleeve. Since the sleeve 35 has an outside diameter that is greater than the core opening I9,` the sleeve base determines and fixes the uppermost position of the switch within the relay coil.

Associated with the coil I8 is an iron circuit generally designated 31 which comprises yokes 38 and 39, each of which consists of a fiat bar of cold rolled electrical iron bent in the form of a U, the ends of the yokes 38 and 33 overlapping, as shown in Fig. 2, and having vertical apertures lll aligned with the core opening I9. The two yokes form a box-like iron circuit for the magnetic flux set up by the coil and the vertical web of the yoke 39 is spot welded or otherwise secured to a plate 4I which is secured to the panel Il by screws 42.' 'I'he yokes 38 and 39 are also spot Welded or otherwise held together.

In order to improve the electrical qualities of the electric circuit, it is preferably annealed at 1750" F. for a period of approximately live hours before being assembled in the relay.

A brass tube 43 having its lower end spun over, as indicated at 44, is adapted to fit within the core opening I9 and` project above the relay coil. 'I'heY purpose of this tube is to position and hold the coil I 8 within the magnetic circuit 31 thereby preventing the coil from contacting or producing mechanical pressure against the glass envelope; to protect the top of the switch envelope from damage due to accidental blows; and to obscure the arc that has formed within the switch when the relay is being used to control an electrical circuit having a high inductive load.

All metal parts of the relay are cadmium-plated or otherwise suitably finished.

In assembling the relay, the coil I8 is first slipped into place within the magnetic circuit 31 and then the brass tube 43 is thrust upwardly into the core opening I9. Next the switch envelope 20 with its base 35 is inserted from the bottom into the tube 43 until the top of the sleeve 35 strikes the spun edge 44 of the tube 43. At this position, the switch is properly located within the relay coil and will have the desired operating characteristics. tion by 'a retaining cup or protector 45, preferably -of brass, having a wide ilange 46 screwed to the iron circuit 31 by screws 41 to hold the cup in place. The depth of the cup is such that when the screws 41 are screwed tightly into the iron circuit 31, the base of the cup 48, which is apertured as indicated at 49 to accommodate the switch leads 50, will firmly engage the base of theswitch envelope and hold it against the lower edge of the tube 43. Prefer-ably rubber gaskets 5I are interposed as shirns between the base of the sleeve 35 and the cup base 48, in order to better protect the Aswitch from damage due tol blows. It will be noted that the inside diameter of the cup or protector 45 is slightly greater than the outside diameter of the sleeve 35, and this slight .clearance assists in protecting the tube from damage.

In practice, the base 35 and the cup 45 are standardized, so that when once the desired position of the switch has been empiricallyv determined at the factory, it will always be held in this position.

'I'he retaining cup 45 may be quickly removed whenever it is desired to take out the switch for examination and inspection.

In the particular embodiment of the invention shown, one oi the leads 5I) is connected to the terminal clip I6, and the other is connected to a terminal clip 52. A jumper 53 on the back of the panel connects the clip 52 with the clip I2, and a similar jumper 54 connects the clip I3 with the clip I1.-

Instead of having the tube 43 extend through the coil I8 as shown in Fig. 2, it may be made a more or less integral part of the yokes 38 and 39 by using a shorter tube 55 and having its lower end soldered or otherwise secured to the,

top leg of the yokes 38 and 39 (see Fig. 4) Preferably the opening 40 in the top leg of the overlapped yokes is of suiflcient size to permit the bottom of the tube 55 to rest on the lower leg of the overlapped yokes.

The switch is held in this posi- I in Fig. 4 has` the disadvantage that the tube 20 may be damaged by a blow on the coil I8 and for this reason,l it is preferable to have the brass tube 43 extend completely through the coil as shown in Fig. 2.

In auto call systems, such as are used in manufacturing establishments for indicating that a particular person is wanted on the telephone, it is necessary for the relay to be sufllciently fast in its response to the energizing coil to open and close the electrical circuit through the switch element as many as ve or six Ytimes a second. The problem of building a relay for this function is made more diiiicult for the reason that the relay controls a relatively large number of signals which together constitute a high inductive load on the relay. The switch element of the relay must, therefore, have suilicient capacity and stamina to take care of this high inductive load.

In dealing with this'problem, we have foundthat the following factors must be considered:

A. The more iron that is used in the iron circuit and in the armature of the switch, the slower will be the response of the armature to the coil.

B. The weight and buoyancy of the displacer and the proportion of iron to ceramic used in the displacer must be such that when the coil is energized, the displacer Will immediately move to its lower position, and when the coil is deenergized, the buoyancy of the displacer will immediately move the displacer to its uppermost position. Not only is this relationship important, but it is, furthermore, desirable to have the mass of the displacer and the proportionment of iron \to ceramic such that the forces acting upon the displacer to move it from one position to another bear appropriate relation to the frequency of the coil energization andthe duration of each energization. Stated in other words, the switch parts should be constructed so that the displacer will have a natural frequency of oscillation which assists rather than opposes the forces producing the artificial oscillation.

C. In order toy carry the high inductive load, it is desirable to use a mercury to mercury contact, although this necessarily limits the speed at which the relay will operate. If the inductive load is such that a metal to mercury contact may be used, the central electrode may be formed as shown in Fig. 6 in order to get speedier action of the relay.

As a speciflc illustration of how the parts may be proportioned both as to size and material, the following detailed information is given, but it will be understood that this specific illustration `is introduced merely for the purpose of complying with section 4888 of the revised statutes and does not constitute in any way a limitation upon the appended claims unless the prior art demands a more limited construction of the.

claims to preserve their validity.

the bottom (the bottom enlargement belng 1A" high) Iron sleeve 29 11'," long and nl, thick I. D. of ceramic cup 26-- 11/64" O. D. oi' ceramic cup 29- 17/64" Top face of cup inclined approximately 30 from horizontal.

Ceramic sleeve 28 made o! Alsimag No. 35, a product of the American Lava Corporation, Chattanooga, Tennessee.

Iron sleeve 29 made of Svea metal, a product of theSwedish Iron & Steel Co. of New York, N. Y.

'I'he principal dimensions of the iron circuit and of otherv parts of the relay are indicated on the drawing.

In Fig. 5, there is a diagram of the electrical circuit for an auto call system. The signals are indicated at 60, the relay at I0, a power source for the signals at 6I, a power source for the The call board consists of a disk having a plurality of contacts 64 over which a blade 65 pivoted at 66 and rotating at a constant speedis adapted to wipe, the contacts being selectively movable into and out of contact with the rotating blade. When a call is to be made, the proper contacts are set for engagementl with the blade 65 and each time the blade wipes over one of the contacts, an impulse is sent through the coil i8, with the result thatan indication is produced on the signal 60.

The'bank of contacts on the left of the call board 63 (Fig. 5), it will be noticed, are placed closer together than those on the right in the same iigure. These contacts in practice are often set apart at a distance which permits the4 blade to wipe over all of the closely spaced con-I tacts'within the period of one second, and each contact must produce its impulse clearly and distinctly on the signal 60. The necessity for instantaneous operation of the relay l0 is, there fore, apparent. Y*

In practice, the closely spaced contacts produce electrical impulses in which the ratio oi' closed circuit to open circuit is approximately equal.

A spring 61 of the type shown in Fig. 3 of the application of Clarence E. Gehrand and Carl H. Larson, Ser. No. 23,556, led May 27, 1935 is secured to the central electrode and serves as a stop for the displacer in its downward movement in cases where an abnormally high voltage is applied to the coil I8. 'Ihis enables the switch `to vmaintain its speed of action even when the coil I8 is overenergized.

The mercury fill in the envelope is such that when the displacer` 21 is resting on the spring 61, the mercury level is from 3," to Y, above the low edge of the ceramic cup 25.

We claim:

1. In a mercury switch relay, a coil, an iron circuit associated with the coil, a mercury displacement switch mounted within the coil including a vertical switch envelope, a base on the envelope fixing the uppermost position of the envelope within the coil, and a retainer for lsupporting the switch in its uppermost position.

2. In a mercury switch relay, a coil, an iron circuit associated with the coil, a mercury displacement switch mounted within theA coil including a vertical switch envelope, a base on the envelope xing the uppermost position of the envelope within the coil, and a retainer at- `tached to the iron circuit for supporting the switch in its uppermost position.

3. In a mercury switch relay, a coil, an iron circuit associated with the coil, a mercury displacement switch mounted within the coil including a vertical switch envelope, a base on the envelope .xing the uppermost position of the envelope within the coil, and a cup adapted to receive the envelope base and support the switch in its desiredposition. n

4. In a mercury switch relay, a coil, an iron circuit associated with the coil, a mercury displacement switch mounted within the coil including a vertical switch envelope projecting above the coil, means for supporting the switch in the coil, and a sleeve of non-magnetic material around the projecting portion of the envelope. I

5. In a mercury switch relay, a coil, an iron circuit associated with thecoil, a mercury displacement switch mounted Within the coil including a vertical switch envelope projecting above the coil, means for supporting the switch in the coil, and a sleeve o f non-magnetic material around the projecting portion of the envelope, said sleeve being rigid with the iron circuit.

6. In a mercury switch relay, a coil having al core opening, a box-like iron circuit around the coil, a mercury displacement switch mounted vided with apertures aligned with the core open- `ing.

8. In a'mercury switch relay, a coil having a core opening, a box-like iron circuit around the coil, and a mercury displacement switch mounted within the core opening and including a vertical switch envelope, said iron circuit comprising a pair of yokes arranged on opposite sidesof the coil, each of said yokes consisting of a ilat bar bent to U form.

9. In a mercury switch relay, a coil having a core opening, a'box-like iron circuit around the coil, a mercury displacement switch mounted within the core opening and including a vertical switch envelope, a base on the envelope xing the uppermost position of the envelope within the coil, and a retainer for supporting the switch in its uppermost position, said iron circuit comprising a pair of yokes arranged on opposite sides of the coil, each of said yokes consisting of a fiat bar bent to U form.

`10. In a high speed mercury switch relay, the combination of a relay coil, means for intermittently energizing the coil at a rate of several times per second, a mercury switch relay mounted'in operative relation with the coil and comprising a switch envelope, electrodes projectinginto the envelope, a mercury iill, a magnetically responsive displacer shiftable in response to the coil to displace more or less mercury according to its position within the envelope and thereby determine the condition of the electrical circuit through the electrodes, the parts of said relay beingl of such mass and proportions that the displacer has a natural frequency which corresponds roughly with the frequency of energization of the coil.

11. In a high speed mercury switch relay, the combination of a relay coil, means for intermittently energizing the coil at a rate of several times per second. a mercury switch relay mounted in operative relation with the coil and comprising a switch envelope, electrodes projecting into the envelope, a mercury fill, a magnetically responsive displacer shiftable in response to the coil to displace more or less mercury according to its position within the envelope and thereby determine the condition of the electrical circuit through the electrodes, theV parts of said relay being of such mass and proportions that the displaccr has a natural frequency of oscillation which assists rather than opposes the forces producing the articial oscillation.

12. In a mercury switch relay, the combination ofv a coil, an'iron circuit associated with the coil, a mercury switch envelope mounted in the coil and having its upper end projecting a substantial distance beyond the coil and a protector substantially rigid with the iron circuit and telescoped over the switch envelope with the upper -portion of the protector extending substantially to or above the top of the envelope whereby the latter is protected against blows.

13. In a mercury switch relay, the combination of a coil, an iron circuit associated with the coil, a mercury switch envelope within the coil having an end projecting a substantial distance beyond the coil and a protector substantially rigid with the iron circuit and telescoped over the switch envelope with an end of the protector extending substantially to or beyond said projecting end of the envelope whereby the envelope is protected against blows.

14. In a mercury switch relay, the combination .of a coil, an iron circuitassociated with the coil,

15. In a mercury switch relay, the combination of a coil, an iron circuit associatedl with the coil, a mercury switch envelope having its lower end projecting below the iron circuit and a protector substantially rigid with the iron circuit, telescoped over the switch envelope and spaced slightly therefrom with an end of the protector extending substantially to or beyond an end of the envelope whereby the envelope is protected against blows.

16. In a mercury switch relay, the combination of a coil, an iron circuit associated with the coil, a mercury switch envelope having its lower end projecting below the iron circuit and a protector substantiallyV rigid with the iron circuit, telescoped over the switch envelope and,

spaced slightly therefrom with the lower portion of the protector extending substantially to or below the bottom of the envelope whereby the envelope is protected against blows.

17. In a mercury switch relay, a coil, an iron circuit associated with the coil, a mercury switch envelope within the coil, a. base on the envelope xing the uppermost position of the envelope within the coil, a cup receiving the envelope base and xing. the lowermost position of the envelope within the coil, and shim means cooperating with the base for supporting the envelope in desired position within the coil.

18. In a mercury switch relay, the combination of a coill an iron circuit associated with the coil, a mercury switch envelope within the coil having one of its ends projecting beyond the iron circuit, and a protector, substantially rigid with the iron circuit, telescoped over the projecting end of the switch'envelope and extending substantially to or beyond said end of the envelope whereby the envelope is protected against blows.

' CARL H. LARBON.

DANIEL. J. MccARTHY. 40 

